Background: Saliva is the most common biological evidence found at any crime scene next to blood. It is a clear liquid which makes it immune to any possible evidence of alteration by the perpetrator. In forensics, saliva is used as biological evidence and is very helpful in determining various aspects of an individual such as sex, individuality, ABO blood groups, microbial signature, biomarkers, or habits like smoking.Main body: Saliva shares a great resemblance with plasma as it encompasses similar organic or inorganic compound contents. In forensic casework, identifying any evidence is the primary goal to establish the groundwork for further investigation. Saliva may be found in the form of a pool or stained form, but its identification is challenging because of its transparency. It has been widely used as an informative tool in forensic situations like poisoning, hanging, or cases of drug abuse, etc. for more than two decades now. Over the years, many proposed ways or methods have been identified and described, which helped in the detection and identification of saliva as evidence.Conclusion: This review article represents the significance of saliva as important forensic evidence, along with the different forms it may be encountered at the crime scene. The use of diverse collection and detection methods, over the past few decades, has been discussed. An attempt has been made to collect the available data, highlighting the merit and demerits of different identification techniques. The relevant data has been collected from all the published and reported literature (1987–2021).

A latent fingerprint is a shred of inevitable evidence left on a scene of the crime by the offender. Being aware of fingerprints, offenders tend to deteriorate all possible pieces of evidence by different methods that include burning, immersing the evidence in water, and many more. Water-immersed latent fingerprints are still viable for the development process due to the presence of water-insoluble components (Lipids, oils, etc.) in the latent fingerprint. Different methods have been tested for the imaging of water-immersed latent fingerprints among which Small Particle Reagent (SPR) was found to be the most efficient by many researchers. This method involves the application of fine particles suspended in a reagent based liquid medium onto the surface containing latent prints immersed in water, resulting in the development of highly detailed fingerprint impressions. The reagent comprised of hydrophobic head and hydrophilic tails that adhere to latent fingerprint and suspended particle respectively and thus act as a junction among them. The diverse composition of Small Particle Reagent, various surfaces for taking impressions of latent fingerprint (followed by immersing in water), the Shelf life of SPR, immersion time of latent fingerprint, and various immersion medium studied by researchers has been reviewed in this paper. The maximum shelf life of SPR reported by a researcher is 6 months and the maximum immersion time is 45 days. Furthermore, the need for green synthesis of SPR is emphasized due to its toxicity caused by long-term exposure.